Diwali – or the Festival of Lights – is the biggest and brightest of all the Hindu celebrations.

An ancient festival to celebrate the triumph of light over dark and good over evil, Diwali – from the Sanskrit word deepawali – is also significant in other religions including Buddhism, Sikhism and Jainism.

It marks the homecoming of the God Lord Ram after vanquishing the demon king Ravana.

Diwali is also the Hindu New Year and therefore a major holiday in India, although it’s also celebrated by millions across the world, from India, Nepal and Malaysia to right here in the UK, with thousands attending Diwali lights switch-on events around the country.

The main festival night of Diwali takes place on the darkest, new moon night of the Hindu Lunisolar month Kartika – all the better to see the fireworks and enjoy the symbolic burning of lamps and candles.

Hindu devotees gather to offer prayers on the banks of river Ganges in the northern Indian city of Varanasi (Picture: Reuters/Jitendra Prakash)

When is it?

The date of Diwali changes from year to year – it varies according to the Hindu Lunisolar calendar – but it is usually in October or November.

This year the main festivities will take place on Wednesday 11 November, but the preparations began on Monday 9 November and typically rituals and preparations will be going on for five days.

There are other festive days surrounding the main day of Diwali too. The main celebration is marked by Dhanteras (specific to some Northern and Western parts of India), Naraka Chaturdasi on the second day, Deepawali on the third, Diwali Padva (a day to honour married couples) on the fourth day and Bhau-beej, a day to honour siblings, on the fifth.

Dhanteras falls 18 days after Dussehra, which is how Diwali’s date is determined each year.

How is it celebrated?

Lights, lamps, fireworks, music, food, decorations – garlands of marigold-like flowers and jasmine will be sold on stalls all over India.

Homes are decorated with small clay oil lamps called diyas, lit in honour of Lakshmi, the Hindu goddess of wealth, while fireworks will be set off in celebration – often launched into the sky from the streets or snapped on to the pavement at your feet.

Rangoli patterns are created using rice, paint, coloured sand or flower petals – colourful geometric designs for the entrance ways, living rooms or courtyards of houses that encourage and welcome the goddess Lakshmi.

Gifts and sweets may be exchanged, happy Diwali wishes and greetings are sent – increasingly via social media – and lavish festive meals will be prepared, while people like to buy and wear new clothes – making this a huge date in the Indian shopping calendar too.

It’s also a time that sees people thoroughly clean their homes and gardens to welcome in the New Year.

Then windows will be opened so that Lakshmi can enter homes to bring prosperity. The day after Diwali is also the beginning of the new financial year for Indian businesses.

Hindu devotees gather to offer prayers on the banks of river Ganges in the northern Indian city of Varanasi (Picture: Reuters/Jitendra Prakash)

An artist giving final touches to the idols of goddess Kali for the Kali Puja that coincides with the Diwali. The goddess Kali is believed to be an embodiment of shakti and an avatar of Goddess Durga. She is worshipped on a new moon night in states of West Bengal and Orissa. (Picture: Sunil Ghosh/Hindustan Times via Getty Images)

NOIDA, INDIA ñ OCTOBER 22: An artist giving final touches to the idols of goddess Kali for the Kali Puja that coincides with the Diwali on October 22, 2014 in Noida, India. The goddess Kali is believed to be an embodiment of shakti and an avatar of Goddess Durga. She is worshiped on a new moon night in states of West Bengal and Orissa. (Photo by Sunil Ghosh/Hindustan Times via Getty Images)

Diwali is important commercially too – it’s one of the busiest shopping times of the year as it’s traditional to buy new clothes during Diwali (Pictures: Amit Dave/Reuters)

Diwali lanterns (Picture: Dhinal Chheda/flickr)

A street vendor spreads vermilion powder used for worship during the Tihar festival, another name in Nepal for Diwali Reuters/Navesh Chitrakar)

Hindu priests light oil lamps in a formation of the ‘Swastika’, a Hindu symbol of peace (Pictures: Reuters)

A worshipper prays in the temple during Diwali celebrations at Bhaktivedanta Manor Hare Krishna Temple in Watford, England (Photo by Rob Stothard/Getty Images)

On the banks of the Yamuna river the women chant as they walk through the streets of Vrindavan. They are widows who have left or been abandoned by their families. Until recently, they were kept hidden from society and all but forbidden to celebrate. But that is now changing, and local residents cheer the women on as they pass through the streets of the temple-filled town, many proudly wearing brand new saris gifted by a local organisation. (Picture: ROBERTO SCHMIDT/AFP/Getty Images)

On the banks of the Yamuna river the women chant as they walk through the streets of Vrindavan. They are widows who have left or been abandoned by their families. Until recently, they were kept hidden from society and all but forbidden to celebrate. But that is now changing, and local residents cheer the women on as they pass through the streets of the temple-filled town, many proudly wearing brand new saris gifted by a local organisation. (Picture: ROBERTO SCHMIDT/AFP/Getty Images)